- A recent study evaluated how groundwater relates to risk for Parkinson’s disease.
- The study found that the age of groundwater and aquifer type may both impact risk for Parkinson’s.
- These risks are likely related to exposure to certain water contaminants.
- More research into specific contaminants is required, as well as exploration of prevention strategies.
Parkinson’s disease is a chronic and nerve-damaging condition, with older adults more likely to be affected. A focus of recent research was how Parkinson’s disease risk was associated with groundwater.
A new study, whose results will be presented at the American Academy of Neurology Annual Meeting on April 18-22, 2026, in Chicago and online, found that the age of water as well as the water source may affect risk for Parkinson’s disease.
Ultimately, some water may be more likely to be exposed to neurotoxins than others, and more research will be required to dig into specifics and how this can be prevented.
The full study is not yet published in a peer-reviewed journal.
This study was a population-based case-control study. It included 12,370 participants with Parkinson’s disease as well as over 1.2 million matched controls. Participants lived within a three-mile radius of over 1,000 groundwater sample sites.
Researchers looked at the age of groundwater, drinking water sources, and aquifer types. They used these to indirectly look at exposure to neurotoxins.
According to the U.S. Geological Survey, aquifers are water-bearing rocks that can easily transmit water to springs and wells.
There are different types of aquifers that are named in part based on the type of rock present, such as sandstone aquifers or carbonate-rock aquifers. Researchers examined 21 principal aquifers in their research.
Researchers determine water age based on the idea that water at a greater depth is older. This practice looks for tracers like naturally occurring isotopes and manufactured gases.
In general, younger water is more likely to have certain contaminants like pesticides that were introduced by people.
In the current study, researchers accounted for factors like participants’ urban or rural residence and air pollution in their research models.
Participants who got their drinking water from sources supplied by carbonate aquifers had a 24% higher risk for Parkinson’s disease than participants getting water from other aquifer types.
Older groundwater was associated with a lower risk for Parkinson’s disease but only with carbonate aquifers. In this case, with each one-standard deviation in water age, there was a 6.5% lower risk for Parkinson’s disease.
Overall, younger water in carbonate systems had a higher risk for Parkinson’s disease when researchers compared them “with those using Pleistocene-aged water,” which is older water.
Study author Brittany Krzyzanowski, PhD, a health geographer and assistant professor at the Barrow Neurological Institute in Phoenix, AZ, explained for Medical News Today:
“We found that characteristics of groundwater in your town or city — such as the type of aquifer it comes from and the age of the water — are associated with differences in Parkinson’s disease risk. This suggests that environmental toxins in drinking water may play a role in Parkinson’s disease.”
In their presentation abstract, the authors note that, overall, “[t]hese findings suggest that groundwater age and aquifer type contribute independently to [Parkinson’s disease] risk, with newer groundwater posing greater risk, particularly in carbonate systems where contaminant infiltration is more rapid.”
It is important to note that researchers looked at the factors they did as a “proxy for neurotoxicant exposure.”
Thus, the problem is likely not with the groundwater itself. Daniel Truong, MD, a neurologist, medical director of the Truong Neuroscience Institute at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, and editor in chief of the Journal of Clinical Parkinsonism and Related Disorders, who was not involved in the current research, shared his thoughts on the findings,
According to Truong:
“The observed association likely reflects environmental neurotoxicant exposure mediated by hydrogeology, rather than groundwater itself being intrinsically harmful. In other words, the aquifer type determines how contaminants enter drinking water, which in turn may influence Parkinson’s disease (PD) risk. The study reports higher PD risk in carbonate aquifers and ‘younger’ groundwater. It showed PD risk decreased as groundwater age increased, suggesting modern contaminants are likely contributors.”
Krzyzanowski also noted that “different groundwater systems (aquifer types) affect how environmental contaminants move through the ground.“
“Some aquifers allow pollutants like pesticides or industrial chemicals to travel more easily through the ground to reach the drinking water supply,“ she detailed.
Thus, “individuals who rely on well water may face a higher risk of Parkinson’s disease if the water is contaminated with substances such as heavy metals, solvents, or certain pesticides—exposures that previous studies have already linked to Parkinson’s disease,” said Krzyzanowski.
Currently, the full study with all of its related details is unavailable. More information is needed to note the full limitations and what future research is needed
Since the research focused on the Medicare population, the results may not be generalizable to other groups. The data also only show an association rather than a causal link between components of groundwater and Parkinson’s disease.
It is also possible that researchers didn’t account for critical factors, thus allowing for residual confounding. Finally, the study received support from three different sources.
Future research can focus on the possible water contaminants that specifically may increase risk for Parkinson’s disease.
Kryzanowski noted that “more research is needed to identify which specific contaminants in drinking water may be most important.”
Prevention is something that will likely be a long-term goal and something that will likely happen less at the individual level.
Krzyzanowski noted the following strategies may be helpful when it comes to prevention: “Protecting aquifers from toxic contamination, improving monitoring of groundwater pollutants, getting your private wells checked annually, and strengthening water treatment systems could help reduce potential risks.”
Truong also speculated that “If the groundwater hypothesis is confirmed, the future prevention strategy will likely resemble ‘lead exposure prevention’, such as: identify[ing] environmental toxin[s], regulat[ing] them, monitor[ing] water and soil, reduc[ing] exposure population wide.”
